Any suggestions on using aperature (peep) sights?

[Sandcut]

OK, well I finally got the time and had the weather cooperate so that I could take my M&P-15 to the range to try it out and sight it in.

I removed the flip up iron sights that came with it and put an accessory carry handle on top. I was shooting at the 50 yard range and was using the smaller aperature ring to sight in the rifle. Now I got it to the point where I could regularly hit within an area that I can cover with my hand, but I think that I could do better if I was shooting using notch and post-style sights instead of an aperature sight. I just find it difficult to decide if the front post is centered properly in the rear ring. Now I realize that this probably has something to do with acquiring a target quickly while in battle, but I have never really been a fan of peep sights.

Is there some trick to using these?